Morphological and molecular identification of the brown dog tick Rhipicephalus sanguineus and the camel tick Hyalomma dromedarii(Acari: Ixodidae) vectors of Rickettsioses in Egypt

Research (Published online: 18-10-2016)

9. Morphological and molecular identification of the brown dog tick Rhipicephalus sanguineus and the camel tick Hyalomma dromedarii(Acari: Ixodidae) vectors of Rickettsioses in Egypt - Hend H. A. M. Abdullah, Amal El-Molla, Fayez A. Salib, Nesreen A. T. Allam, Alaa A. Ghazy and Sobhy Abdel-Shafy

Veterinary World, 9(10): 1087-1101

   doi: 10.14202/vetworld.2016.1087-1101

Abstract

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Aim: Rickettsioses have an epidemiological importance that includes pathogens, vectors, and hosts. The dog tick Rhipicephalus sanguineus and the camel tick Hyalomma dromedarii play important roles as vectors and reservoirs of Rickettsiae. The aim of this study was to determine the prevalence of Rickettsiae in ixodid ticks species infesting dogs and camels in Egypt, in addition to, the morphological and molecular identification of R. sanguineus and H. dromedarii.

Materials and Methods: A total of 601 and 104 of ticks’ specimens were collected from dogs and camels, respectively, in Cairo, Giza and Sinai provinces. Hemolymph staining technique and OmpA and gltA genes amplification were performed to estimate the prevalence rate of Rickettsiae in ticks. For morphological identification of tick species, light microscope (LM) and scanning electron microscope (SEM) were used. In addition to the phylogenetic analyses of 18S rDNA, Second internal transcript spacer, 12S rDNA, cytochrome c oxidase subunit-1, and 16S rDNA were performed for molecular identification of two tick species.

Results: The prevalence rate of Rickettsiae in ticks was 11.6% using hemolymph staining technique and 6.17% by OmpA and gltA genes amplification. Morphological identification revealed that 100% of dogs were infested by R. sanguineus while 91.9% of camels had been infested by H. dromedarii. The phylogenetic analyses of five DNA markers confirmed morphological identification by LM and SEM. The two tick species sequences analyses proved 96-100% sequences identities when compared with the reference data in Genbank records.

Conclusion: The present studies confirm the suitability of mitochondrial DNA markers for reliable identification of ticks at both intra- and inter-species level over the nuclear ones. In addition to, the detection of Rickettsiae in both ticks’ species and establishment of the phylogenetic status of R. sanguineus and H. dromedarii would be useful in understanding the epidemiology of ticks and tick borne rickettsioses in Egypt.

Keywords: hard ticks, light microscope, phylogenetic analysis, polymerase chain reaction, Rickettsiae, scanning electron microscope.